Crash truck pumps



D. F. THOMAS El AL 2,975,715

March 21, 1961 CRASH TRUCK PUMPS 5 Sheets-Sheet 1 Filed March 24, 1958.Lllllll March 21, 1961 D. F. THOMAS EI'AL 2,975,715

CRASH TRUCK PUMPS 3 Sheets-Sheet 2 Filed March 24, 1958 INVENTOR 0a r/aF Thomas lay/s 5. [rd/7s March 21, 1961 D. F. THOMAS EI'AL 2,975,715

CRASH TRUCK PUMPS 3 Sheets-Sheet 3 Filed March 24, l958 BY Qom.a

CRASH TRUCK PUMPS DrividEThomas, St. Paul, and Louis B. Evans, Hastings,Minn., assignors to Waterous Company, St. Paul, Minn, a corporation ofMinnesota Filed Mar. 24, 1958, Ser. No. 723,363 7 Claims. or. 103-408)vision of a novel means of mounting impellers on an impeller shaft in atwo stage pump. In pumps of this type it is usual practice to have theimpeller inlet of both impellers outwardly of the impellers, so that theposition of one impeller is reversed relative to the other. As a result,the two impellers are of diflerent construction. In the present pump,the inlet to each impeller is on the same side of the impeller so thatboth impellers can be of identical form.

A feature of the present invention resides in the provision of a twostage pump having two identical impellers and in which the second stageimpeller runs within two wear rings on opposite sides of the impellerwhile the first stage impeller runswithin a single Wear ring at theinlet side of the impeller. This arrangement is of advantage as itpermits the discharge pressure of the first impeller to be communicatedto the side of this first stage impeller opposite the inlet sidethereof. This pressure exerts a force against the first stage impellerurging it toward the center of the shaft. This same'firststag'edischarge pressure is exerted against the inlet side of thesecondstage impeller creating a force tending to urge this second stageimpeller toward the center of the pump. Thus, the pressure against thetwo impellers is balanced and the thrust against the supportingshaft isequalized.

A feature of the present invention resides in the provision of animpeller arrangement of the type described in which the impellers arespaced by shoulders upon the suporting shaft which may be formed merelyby providing an enlarged diameter shaft portion between the twoimpellers. As the pressure acting upon both impellers tends to urge theimpellers toward the center of the pump or against the large diametershaft portion, no additional fastening means is required for holding theimpellers from axial movement on the supporting shaft.

A further advantage of this type of construction resides in the factthat the first stage discharge pressure is imposed directly on both ofthe stuffing boxes which are located outwardly of the impellers. Thisarrangement maintains the stutiin'g boxes cool and lubricated and avoidsthe necessity of providing lantern rings and water lines to the stuffingboxes as is usually necessary in pumps of this type where enact thestulfing boxes is subjected to partial vacuum.

A further'feature of the present invention resides in the provision of apump ofthe type described including a ates Patent 7 2,975,715 PatentedMar. 21, 1961 These and other objects and novel features of the presentinvention will be more clearlyand fully set forth in the followingspecification and claims:

In the drawings forming a part of the specification:

Figure 1 is a top plan view of the crash truck pump showing the generalarrangement of parts therein.

Figure 2 is a side elevational view of the pump illustrated in Figure 1.

- including an open ended housing 10 having an attachment flange 11 atthe open end designed to accommodate the fly wheel 12 of an internalcombustion engine, not

illustrated in the drawings, and having a drive shaft 13.

The housing 10 incldues a partition 14 in spaced parallel relation tothe flange 11 which supports a removable mounting plate 15 which acts tonormallyclose an aperture 16' in the partition 14. The mounting plate 15supports a bearing 17 encircling a pump drive shaft 19 provided with asplined end 20 which is engaged in a cooperatively splined socket 21 inthe end of the fly Wheel 1 12 and coaxial with the engine shaft 13.

The casing 10 is provided with a closed side 22 having an opening 23therein axially aligned with the shaft 19. A cup shaped bearing support24 is attached to the closed end 22 to extend through the opening 23 andthe bearing support 24 acts to support a bearing 25 providing a furthersupport for the shaft 19. A tachometer drive gear 26 is mounted on theshaft 19 in the bearing support 24 and drives a worm 27 connected to atachometer to drive the same.

A chain sprocket 29 is intermediate the bearings 17 and 25. A chain 30connects the chain sprocket 29 with a cooperable chain sprocket 31mounted upon the impeller-shaft 32 which is parallel to the shaft 19. Abearing 33 is mounted in the partition wall 14 in a suitable recesstherein. The housing wall 22 is provided with a second aperture 34 inaxially aligned relation to the bearing 33 and a bearing support 35 ismounted in the recess 34 to support a bearing 36. The bearings 33 and 36suport an end of the impeller shaft 32 and support the chain sprocket 31which is keyed or otherwise secured thereto.

A pump mounting plate 37 is secured to the housing wall 22 by suitablemeans and the mounting plate 37 is connected to the pump housing 39 bysuitable connecting webs such as 40. The pump housing 39 is alsopartially supported by a brace 41 which extends generally parallelto'the impeller shaft 32 and acts to connect the chain drive housing 10to the pump housing 39. The housing 39 is horizontally split asindicated at 38 (Figure 2) and the two sections bolted or otherwisesecured together.

The pump housing 39 is provided with an inlet or suction passage 42leading to the intake of the first stage. A suction extension fitting 43is bolted or otherwise secured to the under surface of the housing 39providing an extension of the suction pasage. A flange 44 is provided atthe lower end of the extension 43 for connection with the suction line.The mounting flange 45 at the upper end of the suction extension issecured in surface contact with the undersurface of the pump housing 39and acts to close certain water passages as will be later de scribedmore in detail.

mounted upon the shaft 19 The suction passage 42 communicates with thering shaped suction chamber 46 which in turn is in communication withthe inlet end 47 of the first stage impeller 49. The impeller 49 ismounted upon the impeller shaft 32 and rotates in unison therewith. Apartition wall 50 separates the suction chamber 46 from the impellerchamber 51 and a wear ring 52 is mounted within the partition 50. actingto form a running seal with the cylindrical outer portion 53 of theimpeller 49. A cylindrical flange 54 is provided on the side of theimpeller 49 opposite the inlet side thereof but this flange 54 is freeof contact with the housing wall 55. A volute 56 encircles the impeller49 and is subject to discharge pressure from the impeller 49. As thevolute is in communication with the pressure chamber 58 between theimpeller 49 and the housing wall 55, the side of the impeller oppositethe inlet side is subject to the discharge pressure of the impeller 49.

The impeller shaft 32 is provided with an enlarged diameter centralportion 57 which is of somewhat larger diameter than the shaft portion59 on which the impeller 49 is mounted. As a result, a shoulder 60 isprovided between the shaft portions 57 and 59 against which the impeller49 may abut. As the outer side of the impeller 49 is subject todischarge pressure while the opposite side of this impeller is subjectonly to partial vacuum a force is created holding the impeller 49against the shoulder 60, eliminating the need of other fastening meansfor holding the impeller from axial movement upon the shaft 32.

A manifold 61, a portion of which is illustrated in Figure 4 of thedrawings, acts to connect the discharge from the volute 56 to the intakechamber 62 of the second stage of the pump. A second stage impeller 63is mounted upon the impeller shaft 32 for rotation in unison therewithand has an inlet portion defined within a cylindrical sleeve 64 whichruns within a wear ring 65 supported by a partition wall 66 dividing theinlet chamber 62 from the impeller chamber 67. As the inlet chamber 62is subject to the discharge pressure of the first stage, a force iscreated against the outer or inlet side of the impeller 63 urging thisimpeller against the shoulder 69 provided between the enlarged diameterportion 57 of the shaft 32 and the smaller diameter portion 70 thereofupon which the impeller 63 is mounted.

The impeller chamber 67 extends on both sides of the impeller 63 and awall of the housing is provided with a circular flange 71 whichencircles a circular flange 72 on the impeller 63. A wear ring 73 issupported by the flange 71 to provide a running seal with the flange 72so that the area on opposite sides of the impeller 63 which is subjectto the discharge pressure of the second stage is substantially balanced.As a result, the pressure of the discharge from the first stage exertsthe same inward force against the impeller 63 as the first stagedischarge pressure creates against the outer surface of the impeller 49thus substantially equalizing the forces on opposite sides of the pumpor acting against the impeller shaft 32. As will also be noted, the walldefining the suction chamber 46 is spaced from the shaft 57 as indicatedat 74, providing an annular area large enough to permit essentially freeflow of fluid to the suction chamber 46. A chamber 68 is formed inwardlyof the wear ring 73 which is sealed by the wear ring from the dischargepressure in the impeller chamber 67, and which is subject to first stagesuction. Thus, the inner opposed sides of both impellers are subject tofirst stage suction while the outer sides of 'both impellers are subjectto first stage discharge pressure.

A sealing ring compartment 75 is provided upon the wall 55 of thehousing 39 and accommodates a series of sealing rings 76 encircling theshaft 32 and held in place by the packing gland 77. A sealing ringchamber'79 is also provided in the end of the housing 39 opposite .4 thechamber and accommodates sealing rings 78 which are held in place by apacking member 81.

This arrangement is of advantage as the inner ends of the sealing ringchambers are both subject to first stage impeller discharge pressure. Asa result, a certain amount of fluid is forced along the shaft 32 andinto the sealing ring chamber at each end of the pump, maintaining theseals at a relatively low temperature and providing a lubricant for thepacking. This arrangement is of advantage as otherwise, lantern rings orseal cages are often provided in the sealing ring chamber and water isapplied to the sealing ring chamber through suitable conduits connectedwith the discharge pressure of one or both impellers.

As may be noted in Figure 4 of the drawings and as will be even moreclearly seen in Figure 5 of the draw ings, the housing 39 includesheating water circulation areas 80 in the bottom portion of the pumphousing 39, the undersurfaces of which are normally closed by the flange45 forming a part of the suction extension 43. A cooling water chamber81 is also preferably provided beneath the chain drive housing 10 andthrough which the heating water may flow. A partition wall 82 dividesthe chamber 81 into two compartments connected by a passage 83 at oneend of the partition 82. As shown in Figure 4 of the drawings, the lowerend of the chain drive case is open, and is provided with an outwardlyturned peripheral flange 95. A plate 97 closes the lower open end of thechain case. The cooling water chamber 81 is provided with an open upperend and has a pcripheral flange 96. The plate 97 is bolted or otherwisesecured between the flanges 95 and 96, forming a separating wall betweenthe interior of the chain case and the interior of the water chamber.The partition 82 extends upwardly from the bottom of the water chamber81 into contact with the plate 97.

Heating water for heating the chain drive case and the lower portion ofthe pump housing may be circulated by means of a suitable pump andsource of heated fluid supply through apertures 84 and 85 which areshown in Figure 5 to be closed by plugs 86 and 87 respectively. One ofthe passages 84 or 85 forms a heated liquid inlet while the other formsa heated liquid outlet. The heating chamber 80 at the base of the pumphousing 39 is connected to the heating chamber 81 in the chain drivehousing 10 by meaans of a tubular conduit or pipe 88.

In order to complete the support of the impeller shaft 32, the end ofthe pump housing is provided with an end plate 90 connected to theremainder of the housing by ribs 91 or other suitable means. The plate98 is provided with an aperture 91 therein designed to accommodate thebearing support 92 which supports the bearing 93 encircling the end ofthe impeller shaft 32. A cap 94 is mounted to the bearing support 92 toenclose the end of the shaft.

In accordance with the patent statutes, we have described the principlesof construction and operation of our improvement in crash truck pumps,and while we have endeavored to set forth the best embodiment thereof,

.we desire to have it understood that changes may be made within thescope of the following claims without departing from the spirit of ourinvention.

We claim:

1. In a centrifugal pump, a pump housing, an impeller shaft supported insaid housing, a pair of axially spaced impellers on said shaft, saidhousing including volutes encircling said impellers, said housingincluding an axially extending inlet passage on one side of eachimpeller, said impellers being arranged with the inlet passages facingthe same end of said impeller shaft, said housing including an inletconduit terminating between said impellers in communication with theinlet passage of one impeller and on the side thereof facing said end ofsaid impeller shaft which is on the side thereof closest the otherimpeller and said inlet conduit communicating with the said otherimpeller to first stage discharge pressure, said 4 stantially equalaxial pressure against said impellers tending to urge said impellerstoward each other on said shaft, liquid seals between said housing andsaid shaft outwardly of said impellers, the inner ends of said sealsbeing both subjected to first stage discharge pressure.

6. The structure of claim'5 and in which each of said liquid sealsincludes a series of sealing rings and a packing gland outwardlythereof.

7. In a centrifugal pump, a pump housing, an impeller shaft supported insaid housing, a pair of axially spaced impellers on said shaft, saidhousing including volutes encircling said impellers, said housing havingan axially ex- 2. The structure of claim 1 and including shoulder meanson said shaft between said impellers against which said impellers areurged by said first stage discharge pressure.

3. The structure of claim 2 and in which said shoulder means comprisesthe ends of a larger diametershaft portion on said shaft between saidimpellers.

4. The structure of claim 1 and including sealing means between saidinlet passages and said housing, and including a sealing means betweenthe side of said other impeller opposite the discharge passage and saidhousing.

5. In a centrifugal pump, a pump housing, an impeller shaft supported insaid housing, a pair of axially spaced impellers on said shaft, saidhousing including volutes encircling said impellers, said housingincluding an axially extending inlet passage on one side of eachimpeller, said impellers being arranged with the inlet passages facingthe same end of said impeller shaft, said housing including an inletconduit terminating between said impellers in communication with theinlet passage ofone impeller and on the side thereof facing said end ofsaid impeller shaft which is on the side thereof closest the otherimpeller and said inlet conduit communicating with the side of the otherimpeller opposite the inlet side thereof, said housingincluding apassage leading from the volute of said one impeller to the side of saidother impeller facing said end of said impeller shaft and to the inletpassage of the other impeller subjecting the inlet side of said otherimpeller to first stage discharge pressure,*said housing including apressure chamber on the side of said one impeller opposite said inletpassage thereof communicating with the first stage volute and'subjectingsaid opposite side of said one impeller to firststage dischargepressure, and said housing including a discharge conduit connected tothevolute of said other impeller, first stage discharge pressure on theouter sides of said'impelers providing subtending inlet passage on oneside of each impeller, said impellers being arranged with the inletpassages facing the same end of said impeller shaft, said pump housingincluding a first stage suction chamber on the side of the first stageimpeller facing said end of-.said impeller shaft and communicating withthe inlet passage of one impeller, said housing having a first stagedischarge passage leading from the volute of one said impeller to theinlet side of the other impeller and on the side thereof facing said endof said impeller shaft, said pump housing including a first stagepressure chamber on the side of said one impeller opposite the inletside, in communication with the first stage volute and at the dischargepressure of the first stage, a wear ring supported by said housingencircling each said inlet passage, a cylindrical flange on the side ofsaid other impeller opposite said inlet passage, of said other impeller,and a wear ring supported by said housing encircling said flange, saidwear rings being in sealing "relation to the said other impeller, adischarge conduit '9Q11nected to thevolute of said other impeller, andsaid housing including a chamber on the side of said other impelleropposite said inlet passage on said other impeller and inwardly of saidflange on said other impeller connected to said first stage suctionchamber, the impellers being so arranged that the inlet side of said oneimpeller and said opposite side of said other impeller are subject tofirst stage suction, while the inlet side of said other impeller and theside of said one impeller op posite the inlet side are subject to firststage'discharge ptreisure, thereby equalizing axial pressure on saidimpeller s a t.

References Cited in the file of this patent UNITED STATES PATENTS1,927,543 Doyle Sept. 19, 1933 FOREIGN PATENTS 19,470 Great Britain of1905 645,921 Great Britain Nov. 8, 1950 739,007 Germany Sept. 8, 1943

